This was Paul Wilson's follow up to the very successful Coin and Relic.
It had a bit of a reputation for going erratic at times. This could have been a battery problem. Only use good batteries. There was also a problem with the connector at the control box. It could be pulled out accidently if working in the woods and I don't think the electrics liked this.
Ground balance is fixed so you only have discrimination and sensitivity to worry about. Very good depth for a machine of its time and will hold its own today. Both machines had his own design "Hot Head" type coil, smaller than most stock coils but deep.
I didn't get to try one on the wet beach but the Coin & Relic performed better than most single frequency machines over wet salt. Hopefully the Northstar is the same.
He was in partnership at one time (years back !) which was when the Wilson Neuman detectors were produced. I didn't think their performance was up to much and it must have been in pre motion times. Your Northstar is very different and if working correctly will still deliver the goods. If you do a web search try and find a review for his "Coin Select" which is another interesting design.